Function arguments define short CLI options

Allow function arguments to define a short version of the name as well
as the long version.  The exclude hosts short flag has been changed to a
capitol so it will be less likely to conflict with subcommands.
Added tenant and instance UUID flags

The env dict will now also contain tenant and instance UUID values so
subcommands will not require them explicitly.
Add subcommand documentation

This adds subcommand documentation to both the common help output and to
the individual commands help.